Rotary engine



June 16, 1925.

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L. M. ELLIS ROTARY ENGINE June '16, 1925. 1,542,614

Filed April 7, `1919 :Sheets-sheet s Patented June 16, 1925.

UNITED STATES PATENT OFFICE.

LEWIS M. ELLIS, OF TOLEDO, OHIO, ASSIGNOR, BY DIRECT AND' MESNE ASSIGNMENTS,Y`

TO WINSLOW SAFETY HIGH PRESSURE BOILER COMPANY, F CHICAGO, ILLINOIS,

.A CORPORATION OF ILLINOIS.

ROTARY Application led April 7,

To all whom t may concern.' Be it known that I, LEWIS M. ELLIS, a citizen of the United States, residing at Toledo, in the county of Lucas and State of Ohio, have invented a certain new and useful Improvement in Rotary Engines, of which the following is a full, clear, c oncise, and exact description, reference being had to the accompanying drawings, formlU ing a part of this specification.

My invention relates to rotary engines, and more particularly to the type of rotary engine which comprises a pair of meshing herringbone gear wheels enclosed 1n a closely fitting casing and arranged to rotate under the impact, expansion and reaction, of a working Huid such as steam or compressed air which is admitted into the tooth pockets of the gear wheels.

My invention aims to increase the efficiency of this class of rotary engine by modifying the action and course of travel of the working fiuid, and by making va- Tious improvements in the mechanical construction of the engine to the end of in creasing both the thermal and mechanical efficiencies of the unit. A secondary object of my invention is to p rovide a rotary engine of this type which can successfully and economically employ high pressure steam, with pressures ranging as high as five or six hundred pounds, and obtain complete expansion of vthese pressures in a single engine unit.

More specifically, one of the'impro'vements by which I contemplate increasing the thermal efiiciency of the engine is that of abstracting a maximum degree of .rotative energy from the leakage occurring between the meshing teeth at the line of contact between the rotors. The rotor teeth in the present construction are so designed that practically the en tire reaction energy of this leakage is utilized as rotative force at the peripheries of the rotors. This design of the rotors also affords a large ratio of expansion of the tooth spaces or pockets which enables them to obtain complete expansion of the high pressure steam.

I have also modified the course of flow of the working luid'through the tooth pockets of the rotors, whereby a uni-directional ENGINE 1919. serial in. 288,173.

which are about to receive admission steam, I

and, as a consequence, a large initial condensation takes place. In the present construction the steam is exhausted at or adjacent the ends of the tooth pockets, at the ends of' the rotors` and thus there is no reverse flow of chilled exhaust steam back thru the tooth pockets. The efiiciency of the engine may be further increased by .a jacket about the central part of both rotors, this jacket extending laterally the width of the zone in which cutofl:1 occurs.

To the end of reducing the rotative speed of the rotors under high pressure operation, I have made the rotors of relatively large diameter, by which a lower rotative speed is secured without involving any reduction in the peripheral speed of the rotors. Excessive weight of these large rotors is avoided by constructing them of hollow cylindrical shells which are supported by anti-friction bearings preferably located in the rotor casing adjacent the ends of the rotors. To prevent the high temperatures in the rotor casing from overheating the bearings or vaporizng the lubricating oil therein, I have provided means for protecting the bearings, which is preferably in the form of water cooled jackets disposed between tlie bearings and the high temperature zones. The efiieient lubrication of these bearings is insured by continuously orintermittently circulating a lubricating oil through the bearings, which also acts as a beneficial cooling medium therefor.

In the accompanying drawings, whe-rein I have illustrated a preferred embodiment of my improved rotary engine: A

Figure 1 is a longitudinal sectional view through the rotor casing taken approxi,- mately on the line 1-1 of Figure 2;

Figure 2 is a transverse sectional view taken approximately on the line 2 2 of Figure 1, the central part of the section being taken on a plane mid-length of the rotors; and,

Figure 3 is an end elevational view of the rotor casing showing the piping connections thereto.

The construction employed in the present invention comprises a casing 1 formed with two parallel cylinders 2 and 3 which intersect in the center of the casing and form two adjoining rotor chambers in which revolve the rotors 4 and 5. These rotors are provided with herringbone gear teeth which intermesh at the line of Contact between the rotors, as Ishall presently describe. I preferably make these rotors of relatively large diameter, to secure a high peripheral speed and a correspondingly low rotative speed, and to avoid the excessive weight which a solid construction of these rotors would involve, I construct the rotors of hollow shell construction, as illustrated in Figure 1. Each rotor comprises a pair of cylindrical shells 6 and 7, which are closed at their ends, and are provided with' axial hubs 8 and 9 having bearing support in the casing 1, as I shall presently describe. The shell 7 has a reduced cylindrical extension 11 which is adapted to be pressed into the interior of the shell 6. In constructing these rotors, right hand spiral teeth are generated about: the circumference of one shell, and left hand spiral teeth are generated about the circumference of the other shell. `The two shells l' are then placed in a power press and pressed together into a rigid unit with the spiral teethmatching, thereby forming the V- shaped herringbone teeth 12. The hollow construction of the rotors has a further advantage in that it avoids the large thermal expansion characteristic of solid rotors. Y

The casing 1 is closed off at both ends by end plates 14 and 15 which extend across and cover the ends of both rotor chambers 2 and 3. Stud bolts 10 or the like secure the end plates to the casing. Flach of the end plates 14 and 15 is provided with inwardlyextending circular flanges ltlaligned with each of the axes of the rotors 4 and 5, which ianges carry the outer races of thc ball bearings 17. It will be noted that the rotor hubs 8 and 9 have reduced ends, as indicated at 18, and these reduced ends carry the inner races of the ball bearings 17. The ball bearings 17 carry the radial load of the rotors, and also any slight thrust of the rotors. The thrust load is absorbed by the outer races abutting the end plates 14 and 15 and the inner races abutting the shoulders formed on the rotor hubs 8 and 9. By this construction, the weight of the rotors, and the natural strains and vibration incident to their high speed rotation, are borne entirely by the casing structure. Referring to the shaft 21 of the rotor 5,

it will be noted that this shaft is full floating for the reason that the entire weight of the rotor 5 is supported by the rotor casing. This shaft is supported at one end in the rotor hub 9 by keys or splines 22 seating in milled slots 23 in the end of the hub 9. The other end of the shaft 21 extends out of the rotor casing through the opposite end plate 14. By this arrangement of the shaft and bearings I secure the maximum extent of labyrinth packing on the shaft 21, which will be more apparent as the description proceeds. The shaf. 21 extends freely through the rotor hub 8 and throu h an axial opening in the end plate 14. n the outer end of the shaft 21 is keyed a spur gear 24, or other suitable driving element. This end of the shaft 21 has a bearing support in a ball bearing 25, the outer race of which is carried in a circular iiange 26, which projects laterally from the end plate 14. The gear 24 abuts the inner race of the bearing 25 and any end play of the shaft 21 can be taken up by simply shifting this gear to draw the two splinesl 22 up into the ends of the slots 23. 'lhc shaft 21 is purely a torque shaft as it carries no part ot' thev weight of its rotor 5. The drive from the rotors may be entirelv thru one rotor shaft 21; in which case the other rotor chamber would be completely closed by the end plates 14 and l15, or it may be from both rotor shafts.

The labyrinth packing which I preferably employ for holding the relatively high steam pressure prevailing in the rotor casing, consists of a tube or sleeve 27 encircling the shaft 21, and a series of annular grooves 28 cut in the periphery of the shaft 21. The sleeve 27 is screwed or otherwise tightly secured in thc end plate 14 as indicated at 29, and is extended back along the shaft 21 to a point adjacent the splines 22. A lubricant is supplied to this packing through an oil pipe 31 which threads through the end plates 15 and passes into an axial hole 32 in the end of the shaft 21. A radial hole 33 communicates with the hole 32 and conducts the oil out under the closely fitting sleeve 2T where it. seeps along thc shaft 21, lubricating the packing and filling the annular grooves 28. According to the theory of this labyrinth packing, any steam tending to leak out between the shaft 21 and sleeve 27 undergoes a distinctl drop in pressure each time it encounters a groove 28 uutil the pressure becomes insufficient to penetrate the oil film between the shaft and sleeve. Any excess oil leaking from the inner end of the sleeve 27 is caught in an internal groove 34 in the rotor hub 9, from Which it is whirled out through a radial hole 35 onto the races of the ball bearings 17. A small drill hole 30 excretes any oil trappedin the hollow rotor 5 out into the lili) rotor chamber or casing where it forms an oil film between the rotor and casing. The oil pipe 31 has connection with an oil feed pipe 36 formino' part of a forced feed lubricating system 'or the rotary engine.

Thisv lubricating` system is also intended to lubricate the ball bearings 17 at each end of the rotors 4 and 5, by continuously or intermittently vcirculating a lubricant through these bearings. Referring' to Figure 3 a pipe 37 feets oil to the oil supply-header 38, which supplies oil to both end bearings 17 through couplings 39, (Figure 1). The couplings 39 tap into the end plate 14 adjacent the bottom of the bearings 17, so as to feed the oil upon the surfaces of the outer races. An oil pocket for confining'this oil is formed by screwing a small circular plate 41 to the end of the flange 16 by screws 42. The central opening in this plate 41 is flared to receive an oil retaining ring 43 of felt or the like, which bears upon the surface of the rotor hub and prevents the leakage of oil into the rotor casgl'he oil is maintained below the ring 43 at the level indicated, by an overflow header 44 which connects with the oil pockets of both bearings through couplings 45 and serves to equalize the levels in these pockets. As shown in Figure 3, a T fitting 46 is interposed in the header 44 and communicates with an overfiow pipe 47. The overflow pipe 47 has an upward bend which determines the maximum oil level in the oil pockets, the oil flowing downward by gravity from this bend to the force feed apparatus. of course provided for circulating oil through the ball bearings at the-other end of the bearing/ It will be apparent that this circulation of oil through the bearings provides a very efiicient lubrication of these bearings, and, of still more importance, effectually diminishes the heating of the oil and the bearings from the steam temperatures in the rotor casing.

Referring to Figure 2, it will be noted that the casing 1 `is cored out to provide a steam jacket or chamber 48, in t-he lower part of the casing, which functions to preheat the adjacent walls of the rotor chambers. Steam under boiler pressure is admitted to the chamber 48 through the steam pipe 49 which extends into one end of the casing 1. Midlength of the rotors 4 and 5, the casing 1 is provided with a steam inlet 51 leading up from the chamber 48 and communicating with the two admission ports 52 which admit steam to the tooth spaces or pockets on the rotors 4 and 5.

The herringbone teeth 12 are so generated upon the rotors 4 and 5 that the V-shape-d points 53 (Figure 1) on each rotor move downward through the line of contact be- A similar set of connections is tween the rotors in the operation of the engine. When the V-shaped spaces or pockets between these points come into register with the admission ports 52 steam enters and Hows upward through the pockets to the line of contact between the rotors where the meshing herringbone teeth close the pockets. The impaction of the steam jets issuing from the ports 52 and impinging in the V- shaped pockets formed by the herringbone teeth produce the initial rotative force acting .upon the rotors. When the V-shaped pockets, which I shall designate 54, revolve past the admission ports 52, the admission of steam thereto is interrupted, and the steam confined therein begins to expand by enlarging the pockets through rotation of the rotors. The expansion of the steam continues until the ends of the tooth pockets 54 rotate past the line of contact between the rotors and clear the teeth of the other rotor, whereupon the steam is free to exhaust into the exhaust chambers 55 at the ends of the rotors (Figure l).

The rotors 4 and 5 have a close fit in the rotor chambers 2 and 3 with a very minute clearance to avoid metal to metal contact. It would appear that leakage across the tips of the teeth would be inevitable, but it must be remembered that each successive tooth pocket clearing the admission port contains steam at but a slightly higher pressure than the preceding pocket, and hence any leakage forward across the tips of the teeth is from one pressure area to a pressure area of but slightly lower pressure, and is therefore negligible. This action is analogous to that of the labyrinth packing previously described. Any steam leaking backward over the tips of the teeth imparts leaction energy to the rotors and is utilized in the succeeding tooth pockets.

The herringbone teeth on the rotors 4 and 5 are generated with practically no bottom clearance in order to secure a very closeI mesh or line of contact between the rotors. Nevertheless, there is likelihood of some leakage between these intermeshingteeth, particularly when using the high steam pressures which I contemplate using. and to minimize the loss of energy from this source, I have diminished the pitch angle of the herringbone teeth to such an extent that the leakage is in reality converted into reaction energy tending to increase the torque at the peripheries of the rotors. This conversion of the leakage into reaction energy will be, obvious from the low pitch angle of the teeth illustrated in Figure 1` where it will be seen that the reaction component of the leakage-which is in the line df the spiral tee-tl1-s11bstantially coincides with the turning force, which is that force acting at right angles to the rotor axis. The slight end thrust which results from the Obliquity of the reaction component is of course neutralized by the opposite end thrust from the other half of the rotor. The steam leaking past the line of contact between the rotors has immediate access to the exhaust chambers thru the tooth pockets above the line of contact, which pockets are in exhaust position. The low pitch angle of the herringbone teeth has the further utility of increasing the expansion ratio of the tooth pockets. The ratio of expansion may be of any predetermined amount, governed by the location of the admission ports, the length of the rotors and the pitch angle of the teeth. I also contemplate varying the ratio of cxpansion by the use of adjustable admission ports. In the presentl instance, the pitch angle and length of rotors have been designed to obtain expansion periods corresponding to 270 degress of rotation of the rotors. That is to say, the tooth pockets expand through approximately 270 degress of rotation between admission and exhaust. Any condensation taking place in the tooth pockets is squeezed out from the ends thereof into the exhaust chamber 55 at the line of contact between the rotors. The provision of the steam chamber 48 has the action of heating the V-shaped point or ridge of metal 57 to a relatively high temperature. This ridge of heated metal tends to preheat the teeth as they move away from the point of contact between the rotors, and in a large measure reduces the condensation occurring in the tooth pockets 54.

The exhaust chambers 55 are common to the corresponding ends of both rotors, and have outlet connection through ports 56, with exhaust passages 56 in the base of the casing 1, which connect with a suitable exhaust manifold. The exhaust is frequently at temperatures suHieiently high to affect the lubricating oil and heat the ball bearings 17, and for this reason I contemplate providing water cooled jackets or chambers for protecting these bearings from the exhaust steam in the chambers 55.

As shown in Figure 1, these cooling chambers consist of circular water jackets 58 formed either as castings or of sheet metal, as desired. These jackets are conformed to fit snugly over the annular flanges 16 and are secured to the end plates 14 and 15 by screws 59.

The jackets are formed with reduced portions 58 which extend in toward the rotor shaft and closely embrace the ball bearings 17. The bearings 17 are thus enclosed on all sides and are protected from the exhaust by a non-conducting wall of water. An independent water jacket 58 may be made for each ball bearing or a single jacket may extend across from one rotor shaft to the other for housing both bearings.

A continuous or intermittent circulation of cold water through these jackets is secured by the cold water inlet header 61 and the outlet header 62, shown in Figure 3. The inlet header 61 has short sections of pipe 63 tapping through the end plates 14 and 15 and into the lower parts of the jackets 58. The outlet header 62 has similar sections of pipe 64 tapping into the upper extremities of the jackets 58. The headers 61 and 62 are connected thru pipes 65 and 66 respectively, with any source of cold water supply. A similar set of connections is of course provided for circulating cooling water thru the water jackets at the other end of the casing.

'Various modifications will immediately suggest themselves to those skilled in the art, but I intend that such modifications shall come within the spirit and scope of the a pended claims.

I c aim:

1. In a rotary engine, a casing formed with two parallel intersecting cylindrical chambers, rotors in each of said cylinders having intermeshing herringbone teeth formed thereon, each of said herringbone teeth extending 180 degrees about the periphery of said rotors, each of said rotors comprising two hollow cylinders, one of said cylinders having a reduced flange thereon adapted to engage in said other cylinder.

2. In a rotary engine, a casing comprising two cylindrical rotor chambers, and a shaft for said rotors, said rotors each comprising two hollow cylinders spaced away from said shaft, one of said cylinders having a reduced flange thereon adapted to engage in the said other cylinder, said cylinders having opposing spiral teeth generated thereon.

3. In a rotary engine, a casing comprising two cylindrical rotor chambers, rotors in said chambers, and a shaft for said rotors, each of said rotors comprising hollow cylinders spaced away from its respective shaft, said shaft extending through said cylinder and having driven connection with only one end thereof and projecting from said casing at the opposite end of said cylinder.

4. In a rotary engine, a casing comprising intersecting rotor chambers, rotors in said chambers, bearings for said rotors, said-bearings being supported at a plurality of circumferential points by said casing, and a floating torque shaft for one of'said rotors.

5. In a rotary engine, ancasing comprising intersecting rotor chambers, rotors in said chambers, bearings for directly supporting said rotors in said casing, and a full floating torque shaft for one of said rotors, said shaft having driven connection with its associated rotor adjacent one end thereof and projecting out of the other end of said casing;1

6. a rotary engine, a. casing comprising two parallel intersecting rotor chambers, rotors in said chambers having meshing spiral teeth thereon, a torque shaft for one of said rotors projecting out of said casing, said rotor being spaced away from said shaft, and a labyrinth packing on said shaft, said packing extending into the hollow interior of said rotor whereby a relatively long length of packing is obtainable between the end walls of said casing.

7. In a rotary engine, a casing comprising two parallel intersecting rotor chambers, rotors in said chambers having meshing spiral teeth thereon, a power shaft for one of said rotors projecting out of said casing, said latter rotor being of hollow cylindrical construction, and a labyrinth packing on said power shaft in the interior of said hollow rotor comprising a sleeve secured to one end of said casing and extending into said rotor.

8. In a rotary engine, a casing comprising two parallel intersecting rotor chambers, rotors in said chambers having meshing spiral teeth thereon, bearings carried by said casing for su porting the weight of said rotors, a full oating torque shaft for one of said rotors, the torque shaft having driven connection with one end of its rotor and projecting out of said casing at the opposite end, said rotor being spaced away from said shaft, and a packing for said shaft comprising a stationary sleeve on said -shaft extending from said casing into the `315. interior of said rotor, and a plurality of grooves in said shaft.

9. In a rotary engine, a casing comprising two parallel intersecting rotor chambers, rotors in said chambers having meshing spiral teeth thereon, bearings carried by said casing for supporting the weight of said rotors, a full floating torque shaft for one of said rotors, said torque shaft having driven connection with one end of its rotor and projecting out of said casing at the opposite end, said rotor being spaced away from said shaft, a packing for said shaft comprising a stationary sleeve on said shaft extending from said casing into the interior of said rotor, a plurality of grooves in said shaft, and a lubricating passage in said shaft for supplying lubricant to said packing sleeve.

10. In a. rotary engine, a casing comprising two parallel intersecting cylinders, hollow rotors in each of said cylinders having meshing spiral teeth thereon, the beginning of the pockets formed by said spiral teeth being substantially free at the ends of said rotors, and an admission port for admitting working fluid at said beginning of the tooth pockets, exhaust ports at the ends of said rotors for receiving the Working fluid after expandin through said pockets, anti-friction bearings adjacent said exhaust ports subject to the temperatures thereof, and circular sheet metal cooling jackets separate from said casing for protecting said antifriction bearings.

In witness whereof I hereunto subscribe my name, this 4th day of A ril, 1919.

LEWI M. ELLIS. 

